The presidential primaries have thrown up almost constant shocks and surprises. But there is one thing that stunned everyone in politics: the unexpected impact of Chuck Norris.

Of course, as many TV villains can testify, no one ever sees Chuck Norris coming. Or at least not until it's too late. Then he kicks you in the face. Yet to the amazement of pundits everywhere, Norris has transformed the Republican race. The actor and martial arts expert helped bring conservative candidate Mike Huckabee to a wider audience. It also marked Norris's arrival as a political force.

Norris endorsed Huckabee late last year in a video posted on YouTube, which became an enormous hit at a time when Huckabee's campaign could hardly afford TV advertising. Since then, he has campaigned tirelessly for Huckabee and Huckabee has returned the compliment by citing Norris as part of his trademark folksy campaign speech. It worked, too. When Huckabee won the Iowa caucus, they saw Norris standing right beside him.

Nor has Norris's influence lessened as Huckabee has gone on to be a major player in the Republican race. At a recent rally in South Carolina, Huckabee launched into an outline of his plans for a strong army. He said it would be 'Chuck Norris approved'. It was a joke. Probably.

The emergence of Norris has to count as one of the strangest reinventions in recent US pop culture. Most Americans know him for his role as Cordell Walker, a monumentally tough Texan lawman best known for his trademark 'round house' karate kicks to the heads of his enemies.

To say Walker, Texas Ranger is kitsch is an understatement. It became a favourite mocking point of late-night TV chat show hosts like Conan O'Brien. Its cheesiness also spawned a website called chucknorrisfacts.com, which lists bizarre claims about Norris's supposed superhuman strength. An example: 'When Chuck Norris falls in water, Chuck Norris does not get wet. Water gets Chuck Norris.'

In fact, the kitsch factor of Norris's public image masked someone who has taken conservative politics very seriously. Norris has been writing a weekly political column for some time, in which he espouses deeply conservative views on gun control, being anti-abortion and openly Christian, and not believing in evolution. To no one's surprise, he also wants a strong military and an aggressive foreign policy that could politely be described as 'muscular'.

Norris has even been a stand-in host for a current affairs talk show on the conservative Fox News channel. It is no wonder that Norris and Huckabee are such a perfect match. 'Chuck Norris is kind of the perfect iconic representative of this campaign,' said Professor Bob Thompson, an expert in popular culture at Syracuse University, New York.

But behind the kitsch, the cheese and the politics lies a fascinating personal story. Norris was born in Oklahoma and is half-Cherokee. He was teased about his mixed-race background at school and ended up joining the air force. It was there he took up martial arts and eventually left the military, opening a chain of karate schools. He took part in karate tournaments and broke into films, playing opposite Bruce Lee in Way of the Dragon. He then starred in a series of war films, such as Delta Force, before taking up a TV career with Walker in the 1990s.

However, he seemed doomed to be seen as nothing more than the butt of student jokes. But experts say it should come as no surprise that Norris has been such a boon to a political candidate. Thompson points out that many conservatives and older people see shows like Walker as good examples of old-fashioned values. 'These are shows where you know who the bad guys are and the good guys win,' said Thompson. 'There is no one saying anything negative about this guy,' he said.

There is also a long history in America of some pop culture figures making the transition to high political office. Take Arnold Schwarzenegger, who went from body builder to action star to governor of California. No one makes 'I'll be back' jokes any more. Or Ronald Reagan, victor of the Cold War and star of Bedtime for Bonzo.

There are even odder examples. Ben Jones played the mechanic Cooter in the show Dukes of Hazzard before turning to politics and becoming a Georgia congressman. There is Fred Grandy, also a respected congressman, but whose first claim to fame was as Gopher on The Love Boat. With a history of turning kitsch into clout, no one should be surprised if Norris is only just starting his political career. 'We have not seen the last of this,' said Thompson.

Heroic humour

What chucknorrisfacts.com says about its hero:

· When the bogyman goes to sleep every night, he checks his closet for Chuck Norris.

· Chuck Norris does not read books. He stares them down until he gets the information he wants.

· There is no theory of evolution. Just a list of creatures Chuck Norris has allowed to live.

· What was going through the minds of Chuck Norris's enemies before they died? His shoe.